1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for manufacturing a semiconductor device including the step of evaluating electrical characteristics.
2. Description of the Background Art
In manufacturing of a semiconductor device, electrical characteristics of a semiconductor element formed on a semiconductor substrate are determined. These electrical characteristics are evaluated based on a state of a wafer or a state of a chip. Here, a wafer or a chip (a subject) is initially fixed to a chuck stage while a ground surface of the subject is brought in contact with a surface of the chuck stage by vacuum suction or the like.
Then, for electrical input and output to and from the subject, a contact probe is brought in contact with a prescribed electrode of the subject. In a case that electrical characteristics of a semiconductor device for electric power (a power device) as a semiconductor device are evaluated, a contact probe having multiple pins (a plurality of pins) has conventionally been employed as the contact probe in order to meet demands or the like for evaluation of electrical characteristics with a high current and a high voltage.
Under such circumstances, it has been known that, during evaluation of electrical characteristics of a subject, a partial discharge phenomenon occurs, for example, between a contact probe and the subject and thus such a disadvantage as partial breakage of a measured portion is caused. If the subject in which partial discharge has occurred is transferred to a subsequent step as a non-defective item, it is very difficult to extract the subject in which partial discharge has occurred.
Therefore, it is important to take measures in advance for suppressing partial discharge, and various proposals have been made. For example, Japanese Patent Laying-Open No. 2003-130889 has proposed a technique to evaluate electrical characteristics of a subject while it is immersed in an insulating liquid. In addition, Japanese Patent Laying-Open No. 10-96746 has proposed a technique to conduct electrical measurement while a subject is arranged in an atmosphere of an inert gas.
In the conventional techniques, however, the following problems are assumed. Initially, in the technique to immerse a subject in an insulating liquid, a contact probe relatively expensive is required as a contact probe. In addition, since electrical characteristics are evaluated in the insulating liquid, it takes time for evaluation, which is considered as one factor interfering with suppression of production cost.
Moreover, in a case that a subject is a semiconductor element in a wafer test or a chip test, it is also necessary to completely remove the insulating liquid from the semiconductor element after evaluation of electrical characteristics ends, and it is considered that a series of evaluations is complicated and cannot easily be applied.
On the other hand, in the technique to arrange a subject in an inert gas, a construction of an evaluation apparatus is complicated and it takes time for evaluation of electrical characteristics. Therefore, this technique is also again considered as one factor interfering suppression of production cost.